Techniques for implementing transformers with center-taps are described. Based on an overlay winding structure, according to one embodiment, the primary and the secondary of the transformer are respectively formed on two separate layers that are stacked on top of each other, wherein the secondary includes two segments, the two respective terminals of the two segments are coupled together to a component in a circuit to form a center-tap of the secondary. According to another embodiment, three or more separating windings are formed on separate layers. At least one of the windings is a conducting stripe wound in loops and includes a center-tap that extends across but not electrically connected to the loops of the conducting stripe by detouring the conducting stripe through other layers.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A transformer implemented in an integrated circuit, the transformer comprising: a first conducting stripe wound into a first flat spiral on a first layer; and a second conducting stripe wound into a second flat spiral on a second layer, the second conducting stripe including at least two segments, each having two terminals, wherein the first and second layers are stacked on top of each other and each of the two terminals of the two segments is coupled together to a connector in the integrated circuit, wherein a primary winding of the transformer is formed by the first conducting stripe, and a secondary winding of the transformer is formed by the second conducting stripe with the each of the two terminals of the two segments connected together as a center-tap of the secondary winding.
2. The transformer as recited in claim 1 , wherein the connector is a terminal of a component in the integrated circuit.
3. The transformer as recited in claim 1 , wherein the connector is a voltage or a ground of the integrated circuit.
4. The transformer as recited in claim 1 , wherein the first conducting stripe includes a center-tap.
5. The transformer as recited in claim 4 , wherein the first and second conducting stripes respectively extend to two or more other layers that are stacked with the first and second layers so that inductance of each of the first and second conducting stripes is increased.
6. The transformer as recited in claim 1 , wherein at least one of the first conducting stripe and the second conducting stripe is extended to one or more additional layers to increase inductance thereof.
7. A transformer implemented in an integrated circuit, the transformer comprising: a first conducting stripe wound into a first flat spiral on a first layer; a second conducting stripe wound into a second flat spiral on at least a second layer; a third conducting stripe wound into a third flat spiral on at least a third layer; and wherein the first, second, and third layers are on top of each other, the first, second, and third conducting stripes are electrically not connected, and at least one of the first, second, and third conducting stripes includes a middle connector to be a center-tap.
8. The transformer as recited in claim 7 , wherein the first conducting stripe is wound a number of loops around the first flat spiral and includes a middle connector extending across but not electrically connecting to the loops of the first conducting stripe to be a center-tap.
9. The transformer as recited in claim 7 , wherein the first conducting stripe extends to the second as well as the third layer to avoid electrical connection to the middle connector on the first layer.
10. The transformer as recited in claim 8 , wherein each of the second and third conducting stripes includes a center-tap.
11. The transformer as recited in claim 9 , wherein the second conducting stripe extends to the third layer to increase inductance thereof.
12. The transformer as recited in claim 11 , wherein the third conducting stripe extends to the second layer to increase inductance thereof.
13. The transformer as recited in claim 7 , wherein at least one of the first conducting stripe, the second conducting stripe and the third conducting stripe is extended to one or more additional layers to increase inductance thereof.
14. A method for implementing a transformer in an integrated circuit, the method comprising: winding a first conducting stripe into a first flat spiral on a first layer; and winding a second conducting stripe into a second flat spiral on a second layer, the second conducting stripe including at least two segments, each having two terminals, wherein the first and second layers are stacked on top of each other and each of the two terminals of the two segments is coupled together to a connector in the integrated circuit, wherein a primary winding of the transformer is formed by the first conducting stripe, and a secondary winding of the transformer is formed by the second conducting stripe with the each of the two terminals of the two segments connected together as a center-tap of the secondary winding.
15. The method as recited in claim 14 , wherein the connector is a terminal of a component in the integrated circuit.
16. The method as recited in claim 14 , wherein the connector is a voltage or a ground of the integrated circuit.
17. The method as recited in claim 14 , wherein the first conducting stripe includes a center-tap.
18. The method as recited in claim 17 , wherein the first and second conducting stripes respectively extend to two or more other layers that are stacked with the first and second layers so that inductance of each of the first and second conducting stripes is increased.
19. A method for implementing a transformer in an integrated circuit, the method comprising: winding a first conducting stripe into a first flat spiral on a first layer; winding a second conducting stripe wound into a second flat spiral on a second layer; winding a third conducting stripe wound into a third flat spiral on a third layer; and wherein the first, second, and third layers are on top of each other, the first, second, and third conducting stripes are electrically not connected, and at least one of the first, second, and third conducting stripes includes a middle connector to be a center-tap.
20. The method as recited in claim 19 , wherein the first conducting stripe is wound a number of loops around the first flat spiral and includes a middle connector extending across but not electrically connecting to the loops of the first conducting stripe.
21. The method as recited in claim 20 , wherein the first conducting stripe extends to the second or third layer to avoid electrical connection to the middle connector on the first layer.
22. The method as recited in claim 20 , wherein each of the second and third conducting stripes includes a center-tap.
23. The method as recited in claim 22 , wherein the second conducting stripe extends to the third layer to increase inductance thereof.
24. The method as recited in claim 23 , wherein the third conducting stripe extends to the second layer to increase inductance thereof.
25. The method as recited in claim 19 , wherein at least one of the first conducting stripe, the second conducting stripe and the third conducting stripe is extended to one or more additional layers to increase inductance thereof.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
July 22, 2003
November 29, 2005
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